Magnetic alloy



Patented Mar. 22, 1927.

UNITED STATES WILLOUGHBY STATHAM SMITH, OF IBENCHAMS, NEWTON POPPLEFORD, AND HENRY JOSEPH GARNETT, OF LYMNE, SOLEFIELDS, SEVENOAKS, ENGLAND.

MAGNETIC ALLOY.

No Drawing. Original application filed January 10, 1924, Serial No. 685,432, and in Great Britain August 25, 1923. Divided and this application filed May 2, 1925. Serial No. 27,594.

This apil ication is a division of our application 1924. D

This invention relates to the production of alloys possessing a high magnetic permeability especially at low magnetizing forces.

It is well known that it is desirable toadd inductance to telegraphic and telephonic cables and this has before been done by wrapping around the core of the cable an iron tape or wire. a

'Many research workers have been investigating the properties of various alloys, especially those of nickel and iron. with a view to discovering an alloy that should be In order also to increase the electrical resistance of the alloy we preferably add tc it a fourth element which may be tungsten,

- be added to secure an increased electrical resistance.

The following is an example ofan alloymade in accordance with this invention.

An alloy consisting of Per cent.

Nickel 73.75 Iron 20.0 Copper 4.5 Manganese 1.75

has an electrical resistance of 26 microhms er. No. 685,432, filed January 10,

per cubic centimetre and an initial magnetic permeability of 4800.

This alloy is sensitive to heat-treatment and should be annealed by heating to a considerable temperature and then cooled. This may conveniently be done by passing a wire or tape formed of the alloy through a tube heated electrically and allpwing the wire or tape to cool rapidly as it issues from the tube.

If the correct temperature has not been used the magnetic properties will not be fully developed.

The annealing may be adjusted to give either (a) Maximum initial permeability, or (6) maximum permeability at magnetic saturation, and (0) low or high fields for magnetic saturation.

Ewample.

The above mentioned alloy- (1.) Annealed at 850 C. and air cooled; initial permeability, i800; saturation permeability, 12300; field for magnetic saturation. .35 0,, g. s. units.

(7)) Knnealed at 830 C. and cooled more slowly; initial permeability, 4700; satura tion permeability, 30000; field for magnetic saturation, .10 c. g. s. units.

Morcoven. when correctly annealed for high initial permeability. the alloys have low hysteresis losses varying fron 50 to 150 ergs per cubic centimetre with a maximum field of .25 c. g. s. units.

hat we claim is 1. An alloy consisting of nickel 73.75%. iron 2011', copper 4.50? and manganese 1.75%.

2. An alloy consisting ot'nickcl from 73 to 74?}. iron 20 to 21%, copper 4.5 to 5.4"? manganese to 2%. and another element adapted to increase the electrical resistance of the alloy.

In testimony that we claim the foregoing as our invention we have signed our names this twenty-first day of April, 1925.

l VILLOUGHBY STATHAM SMITH. HENRY JOSEPH GARNETT. 

